Alkane acetates produced by oxidative esterification of olefins over ammonium borate in the presence of a carboxylate ion source

ABSTRACT

A process for the production of alkane acetates from olefins in the presence of an ammonium borate catalyst, oxygen and a carboxylate ion source via oxidative esterification is described. The reaction is conducted at a temperature in the range of 80° to 280° C. and a pressure of 1 atmosphere or greater. Alkane diacetates and hydroxy acetates are produced which may be used as precursors to alkylene oxides, alkylene glycols and other useful compounds.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. 402,664,which relates to a method for producing alkane acetates by oxidativeesterification of olefins over transition metal borate catalysts in thepresence of acetic anhydride. Thallium borates are used as catalysts inU.S. patent application Ser. No. 402,665, alkali metal borates are thecatalysts in U.S. patent application Ser. No. 402,668, and alkali earthmetal borates are the catalysts in U.S. patent application Ser. No.402,667, all in the same or similar reactions. All of these patentapplications are filed of even date.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to a process for the production of alkaneacetates by the oxidative esterification of olefins, and is particularlyrelated to such a process conducted in the presence of a carboxylate ionsource and ammonium borate.

2. Description of Relevant Methods

The production of ethylene oxide from ethylene has long been known.However, there has been a less successful search for a similar processfor producing propylene oxide directly from propylene in an economicmanner. The same processes which produced ethylene oxide cannot beadapted to the production of propylene oxide.

As a result, a number of different schemes to produce propylene oxidefrom propylene or to produce an intermediate to propylene oxide frompropylene have been proposed. Initially the research effort seemed to bedirected to producing an olefin oxide directly from the olefin in thepresence or absence of a solvent. U.S. Pat. No. 2,649,463 describes theproduction of a coordination complex created by the reaction of anolefin with a metal halide where the metal is copper, platinum,palladium, iridium, aluminum, zinc, silver, mercury or antimony. Thiscoordination complex is further reacted with oxygen at a hightemperature to produce the olefin oxide plus oxygen-containing metalhalides. Hawkins, et al. in an article entitled, "Autoxidation ofOlefins," in the Journal of Applied Chemistry, Vol. 6, 1956, pgs 1through 10, describes a process for the production of epoxides directlyfrom olefins and molecular oxygen over magnesium oxide and/or cobaltnaphthenate. The direct production of olefin oxides from a mono olefinand a saturated hydrocarbon with oxygen and water, organic acids orolefin oxide in low concentration is described in U.S. Pat. No.2,780,634.

British Pat. No. 1,582,261 describes how propylene may be reacted withoxygen over a dinitrogen tetraoxide catalyst in a liquid medium of achlorinated organic solvent to produce propylene oxide directly.Propylene oxide may also be prepared directly from propylene and oxygenover a catalyst system comprising a palladium cation plus a chlorideanion in the presence of a phosphorous or arsenic ligand as revealed inU.S. Pat. No. 4,256,649.

Further, U.S. Pat. No. 2,784,202 outlines how propylene in a liquidhydrocarbon solvent, such as benzene, in the presence of oxygen andwater, organic acids or propylene oxide in low concentration yieldpropylene oxide when heated at a temperature between 130° and 300° C.Propylene oxide is also proposed to be made directly from propylene inbenzene in the presence of oxygen over a cobalt, copper, magnesium,vanadium or chromium catalyst where barium or lead is used as a promoterfor the catalyst, according to U.S. Pat. No. 3,071,601. Brill, et al. inJournal of Organic Chemistry, Vol. 29, 1964, pgs 140-143, describes aprocess for passing olefins and oxygen, frequently in contact with ordissolved in benzene over various catalysts such asazobisisobutyronitrile, cadmium oxide, cobaltic acetylacetonate,magnesium oxide or methyl ethyl ketone peroxide to produce variousoxidation products, including the desired epoxides. U.S. Pat. No.3,132,156 reveals that ethylene, propylene or butylene oxide may beproduced directly from ethane, propane or butane under very preciseconditions. These conditions include a temperature of between 425° to575° C., an oxygen volume percent of between 4 and 14, a contact timewith the oxygen of between 0.07-1.5 seconds, a pressure of between 20 to150 psig and constant concentrations of reactants. Epoxides may also beproduced from olefins and oxygen which are in an inert reaction mediumwhen they are brought in contact with a rhenium catalyst and 0.05 to 15weight percent of a reaction modifier comprised of an alkyl aryl orcyclo alkyl cyanide, pyridine or quinoline in accordance with theinvention described in U.S. Pat. No. 3,316,279.

Other schemes for producing olefin oxides from olefins and oxygen bymeans of a solvent or liquid reaction medium include the following. U.S.Pat. No. 3,153,058 employs polyacyl esters of polyhydroxy alkanes,polyhydroxy cycloalkanes, polyglycols or mixtures thereof as thesolvent. Materials selected from saturated aliphatic, alicyclic andaromatic nitriles and mixtures thereof form the solvent in U.S. Pat. No.3,210,380. Boric acid esters form the liquid reaction medium in U.S.Pat. No. 3,210,381. U.S. Pat. No. 3,228,967 uses major amounts ofacetone as the solvent. Carbonic acid esters are employed in U.S. Pat.No. 3,228,968, and at least 25 percent by weight of certain ketonesserves as the reaction medium in U.S. Pat. No. 3,232,957. Halogenatedbenzenes serve as the solvent in U.S. Pat. No. 3,238,229 while benzoicacid esters are employed in a similar reaction described in U.S. Pat.No. 3,281,433. Olefin oxides may be prepared directly from olefins andoxygen over a hydrocarbon soluble, phosphorous molybdenum-hydroxycompound catalyst according to the disclosure in U.S. Pat. No.3,856,826. The approach of making epoxides directly has never beencommercially feasible because all of the methods explored gave lowyields of epoxides.

At this point in the history of this research, the emphasis seems toshift from making the olefin oxides directly to making an intermediatewhich could be converted to the olefin oxides by a second step. Forexample, U.S. Pat. No. 2,497,408 suggests the production of propyleneglycol diacetate from propylene, oxygen and acetic acid over a metalacetate catalyst in which the metal is lead or iron in combination withan alkali earth metal acetate. Another example of this latter approachis U.S. Pat. No. 3,403,175 where olefins in oxygen are reacted in thepresence of a reaction medium consisting of carboxylic acid andanhydrides with no catalyst to produce glycol diesters. Acyloxycompounds, which are intermediates to olefin epoxides, may be producedby the reaction of olefins with the metal salt of a carboxylic acid inan aqueous solution if electric current is passed through the solution,according to the method of U.S. Pat. No. 3,453,189. U.S. Pat. No.3,479,395 reveals that olefins in oxygen may be converted to glycols andglycol acetates by being brought into contact with a solution comprisingtellurium dioxide, an alkali metal halide and a redox agent dissolved ina solvent of certain specifications (water, acetic acid, dioxane,dialkyl formamides or dialkyl sulfoxides).

Further examples of the approach to making intermediates to the epoxidesinclude U.S. Pat. No. 3,542,857 where vicinal glycol monoesters anddiesters may be made by passing olefins in oxygen in an alkanoic acidmedium over cerium salts. A method for making glycol esters from olefinsand oxygen in a carboxylic acid medium over tellurium and an appropriateform of bromine is revealed in U.S. Pat. No. 3,668,239. British Pat. No.1,278,353 teaches that non-vicinal glycols may be reacted with carbonmonoxide over a rhodium or iridium catalyst together with a halogenpromoter to produce dicarboxylic acids which are precursors to diesterswhich are intermediates to the epoxides. Further, British Pat. No.1,326,219 discloses that glycol esters may be produced from olefins andoxygen in the presence of at least one carboxylic acid when a halogen isemployed as an anion and a metal cation is present which is selectedfrom the group of tellurium, cerium, antimony, manganese, arsenic orcobalt. Other examples which reveal how esters may be made from olefinsinclude U.S. Pat. No. 3,770,813 where an olefin with a chloro, hydroxyor lower alkanoyloxy substituent together with oxygen and a monobasiccarboxylic acid may be reacted together over an iodide anion and a heavymetal cation of atomic numbers 21 to 30 and 48, and nitrogen-containingcations to give glycol esters. Olefins and oxygen may be reactedtogether over a catalyst system comprising a metal cation of tellurium,cerium, antimony, vanadium, gallium, arsenic, copper, selenium or silverwith a bromine or chlorine anion to produce vicinal glycol esters whichare later fractionated to give a residue with a boiling point higherthan the vicinal glycol esters according to the disclosure in U.S. Pat.No. 3,789,065. The residue is then contacted with a carboxylic acid toyield additional vicinal glycol esters. British Pat. No. 1,353,814describes the reaction of olefins and oxygen in a carboxylic acid in theliquid phase that contains at least 0.5 percent water over a catalystsystem identical to that of the patent previously described to alsoyield vicinal glycol esters. Ethylene or propylene may be reacted withoxygen in a carboxylic acid over a catalyst system comprising atellurium cation and a bromide anion or a selenium cation plus achloride or bromide anion to produce vicinal glycol esters as revealedin U.S. Pat. No. 3,907,874.

Aliphatic hydrocarbon carboxylic acid esters of vicinal glycols whichcontain organic halogen impurities may be purified by passing them overaquobasic alkali metal compounds, aquobasic earth metal compounds orcompounds (other than halides) of zinc, lead, cadmium, tin, mercury,silver, manganese, copper, nickel, cobalt, iron or chromium inaccordance with the invention in British Pat. No. 1,410,834. GermanAuslegeschrift No. 2,430,022 describes a multi-step procedure forproducing butane diols, which are precursors to butane oxide, frompropylene, oxygen and acetic acid.

A system which has obtained a fair amount of commercial importance isdescribed in U.S. Pat. No. 4,045,477 by which vicinal hydroxy esters anddiesters are produced from olefins and oxygen over tellurium and aniodide source. Organic monoesters of vicinal glycols may also beproduced from olefins, oxygen, water and a carboxylic acid over a systemcomprising an iodine compound (such as copper iodide, manganese iodideor cerium iodide), a copper compound, and an activated ion taken fromthe group of manganese, cerium, alkali metals, alkali earth metals,nitric compounds or mixtures thereof, according to the invention in U.S.Pat. No. 4,061,868. U.S. Pat. No. 4,069,381 reveals how glycolmonoesters may be made from olefins, oxygen and carboxylic acids over acatalyst system where the cation is zirconium, niobium, molybdenum,hafnium, tantalum, tungsten or rhenium where the anion is a halide inthe presence of lithium, sodium, potassium, titanium, vanadium,chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum orsilver.

Some of the more recent patents in this field include the following.Esters may be produced from olefins in an acid plus oxygen over a tin orcerium catalyst in the presence of iodide as revealed by U.S. Pat. No.4,154,957. Saturated vicinal esters may be produced from olefins,carboxylic acids and oxygen in the presence of a boron-containingcatalyst according to the invention of U.S. Pat. No. 4,220,800. U.S.Pat. No. 4,221,916 teaches that olefins, carboxylic acids and oxygenwhen reacted together over a vanadium or ruthenium-containing catalystcan also produce saturated vicinal esters. U.S. Pat. No. 4,238,624discloses a procedure by which ethylene, oxygen and a lower alkanoicacid are reacted together over an iodine source in a bismuth stabilizedtellurium oxide catalyst on a carbon support to give ethylene glycolmono- and dialkanoates.

Further, alkylene glycol dicarboxalates may be made from carboxylic acidesters of monohydric or polyhydric short chain alcohols and olefins andoxygen over a catalyst system comprising tellurium, cerium, antimony,manganese, vanadium, gallium, arsenic or cobalt, plus a halogen anionand a hydrolyzing agent in addition to water as taught by U.S. Pat. No.4,239,911.

Methods also exist for converting the ester intermediates into theepoxides. For example, U.S. Pat. No. 4,012,423 describes how vicinalhydroxy esters may be reacted over group I, II and IIIA basic metalcarboxylates, being the preferred catalyst (sodium, potassium, lithium,calcium or barium, etc.), or group I, II and IIIA basic metal simpleoxides and complex oxides and organic bases (such as borates,phosphates, oxides and carboxylates, particularly sodium borate, nickeloxide, etc.) to give epoxides. Another method is described in U.S. Pat.No. 4,158,008 whereby propylene glycol monoesters in the presence of ahigh boiling solvent is reacted over a base to produce propylene oxide.Propylene oxide may also be produced from propylene glycol with theremoval of a water molecule over a weakly acidic carrier comprising abasic alkali metal salt of a low molecular weight carboxylic acid astaught by U.S. Pat. No. 4,226,780.

Of the numerous patents discussed so far, the ones considered to be mostrelevant to the invention at issue are U.S. Pat. Nos. 4,012,423;4,069,381 and 4,220,800, all of which have been discussed.

Despite all of the investigative routes described so far and the onesthat have been devised which have not been described, there is still aneed for an efficient method for making propylene oxide from propylene,in addition to making the alkylene oxides from other olefins, which doesnot involve a highly corrosive or highly expensive catalyst system.

SUMMARY OF THE INVENTION

The invention concerns a process for the production of alkane acetatescomprising reacting an olefin or a mixture of olefins with oxygen and acarboxylate ion source in the presence of ammonium borate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Alkane hydroxy acetates and diacetates, also called glycol monoesters ordiesters or vicinal diesters, may be prepared by the oxygen or airoxidation of olefins in a solvent capable of generating a carboxylateion in the presence of ammonium borate. The diacetates may be convertedto epoxides or glycols using methods known in the art, some of whichhave been outlined previously. Both the epoxides and the glycols are ofinterest in the manufacture of important high volume products, includingurethane polyols, gasoline additives, and heat transfer fluids.

According to the method of this invention, the olefin feedstocks mayconsist of any mono olefin having the double bond located anywherewithin the molecule and mixtures of such olefins. The olefin may be analpha or an internal olefin. Specific examples of suitable feedstocksinclude, but are not limited by, the following list: propylene,1-butene, 2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 3-hexene,heptenes, octenes, nonenes, decenes, undecenes, dodecenes, tridecenessuch as 6-tridecene, tetradecenes such as 7-tetradecene, pentadecenes,hexadecenes, etc., and mixtures thereof. Preferably, the olefin has 3 to16 carbon atoms. Propylene is especially preferred.

Of course, molecular oxygen in a pure form or air is an essentialco-reactant for the method of this invention.

The co-reactant and solvent must be a compound capable of generating acarboxylate ion when it serves as a solvent. These compounds may begenerally described as carboxylic acids or anhydrides. They may includematerials such as acetic acid, acetic anhydride, carboxylic acids,although acetic acid and acetic anhydride are the preferredsolvents/co-reactants. Acetic acid is the preferred co-reactant of thisinvention.

Catalysts found to be useful in the method of this invention includeborates. Borate compounds are novel for the catalysis of olefins toolefin acetates and diacetates (also called esters and diesters) neverhaving been previously discovered. It is preferred that the catalyst beammonium borate. This novel catalyst has the formula NH₄ BO₂ in contrastto the formula of NH₄ HB₄ O₇.3H₂ O for ammonium biborate. It iscontemplated that the ammonium borate catalyst of this invention couldbe used in combination with other borate catalysts such as transitionmetal borates, alkali metal borates and alkali earth metal borates in aneffective manner. These catalysts are much less corrosive than many ofthose used in other methods, especially the halide systems. Also, muchsmaller catalyst levels may be used. They are also less expensive thanmany of the catalyst systems proposed.

The reaction conditions under which the method of this invention may beconducted include a temperature range of from 50° to 280° C. A preferredrange is from 120° to 220° C. The pressure may be one atmosphere orhigher. These conditions are much milder than many of those in the priorart discussed earlier.

An initiator may be optionally used to provide an initial source of freeradicals. The use of a readily oxidizable initiator helps to start theoxidation as well as prevent a possible buildup of peroxides which wouldbe dangerous. Aldehydes are suitable initiators with heptaldehyde beingthe preferred initiator. Usually a few drops are enough to be effective;i.e., quantities on the order of 1.0 ml. Peroxides and azo compounds arealso used as initiators.

The invention will be further illustrated by the following exampleswhich are not intended to limit the scope of the invention except asnoted.

EXAMPLES 1-3

A 1-liter 316 stainless steel glass-lined autoclave equipped with amagnetic stirrer was charged with 300 ml of glacial acetic acid andcatalyst. Also present was 1.00 ml of heptaldehyde as an initiator. Theautoclave was sealed, 42 g of propylene pressured in, and the mixtureheated to the desired temperature. Oxygen was added slowly to a pressure50-100 psi higher than autogeneous pressure. The pressure was maintainedby addition of oxygen from time to time (after each addition of oxygenthere was a small exotherm) for the desired reaction time. The reactionmixture was then cooled to room temperature, the reactor vented and thecontents analyzed by vapor phase chromatography. The results are shownin Table I.

Example 2 employed vanadium oxide as a catalyst, which is taught by U.S.Pat. No. 4,221,916. Orthoboric acid was employed in Example 3 as taughtby U.S. Pat. No. 4,220,800. In Example 1 where the ammonium boratecatalyst was used, the weight percent selectivity to esters was higherthan for these two comparative Examples 2 and 3.

                  TABLE I                                                         ______________________________________                                        EXAMPLES ILLUSTRATING THE INVENTION                                                                             Approx.                                                                              Esters                                     Catalyst        Temp.,                                                                              Time, Conv.  Selectivity                          Ex.   ID       (g)    °C.                                                                          (Hr)  %      wt. %                                ______________________________________                                        1     NH.sub.4 BO.sub.2                                                                      1.0    180   5     20     89.7                                 2     V.sub.2 O.sub.5                                                                        1.0    160   5     10     63.4                                 3     H.sub.3 BO.sub.3                                                                       1.0    160   6     14     81.3                                 ______________________________________                                    

Many modifications may be made in the method of this invention by thoseskilled in the art to maximize the yields of the desirable acetateswithout departing from the spirit and scope of the invention which isdefined only by the appended claims. For example, one skilled in the artcould determine ammonium borate catalyst concentrations, temperatures,feedstocks and modes of addition to optimize the yield.

We claim:
 1. An improved process for the production of alkane hydroxyacetates and diacetates by reacting an olefin or a mixture of olefinswith oxygen and a carboxylate ion source selected from the groupconsisting of acetic acid and acetic anhydride, wherein the improvementcomprises conducting the reaction in the presence of ammonium borate. 2.The process of claim 1 in which the reaction is conducted at atemperature in the range of 80° to 280° C.
 3. The process of claim 2 inwhich the reaction is conducted at a temperature between 80° and 180° C.4. The process of claim 1 in which the olefins have 3 to 16 carbonatoms.
 5. The process of claim 1 in which the olefin is propylene.
 6. Animproved process for the production of alkane hydroxy acetates anddiacetates by reacting an olefin or a mixture of olefins where theolefins have 3 to 16 carbon atoms with oxygen and a carboxylate ionsource selected from the group consisting of acetic acid and aceticanhydride, at a temperature of between 80° and 180° C., wherein theimprovement comprises conducting the reaction in the presence ofammonium borate.
 7. The process of claim 6 in which the reaction isconducted at a temperature between 80° and 180° C.
 8. The process ofclaim 6 in which the olefin is propylene.
 9. An improved process for theproduction of alkane hydroxy acetates and diacetates by reacting atleast one olefin having 3 to 16 carbon atoms with oxygen and acetic acidat a temperature in the range of 80° to 180° C., wherein the improvementcomprises conducting the reaction in the presence of ammonium borate.10. The process of claim 9 in which the olefin is propylene.